Cozad Mayor Gregg Tetley says arson was not involved in the explosion and fire at a Cozad dry-cleaning business Wednesday night.
He says the cause has been determined but cannot yet be released due to insurance reasons.
The fire caused homes and schools near the scene to be evacuated. The incident first was reported to a 9-11 operator about 2 p.m.
Emergency officials moved quickly to control the fire and evacuate those homes and schools nearby for fear of problems with chemicals used in the business.
Authorities also shut down U.S. Highway 30 through Cozad for a time.
Red Cross officials say 52 people were at a temporary shelter. Area resident George Culver says everything was very calm.